Mapping fields based on entity

field-mapping.ts

export enum MappingMode {
  SEND = 'send',
  RECEIVE = 'receive'
}

export type MappingEntity = 'contact' | 'deal' | 'organization'

export type FieldMapping = {
  sourceField: string
  destinationField: string
}

export type FieldMappings = Record<MappingEntity, FieldMapping[]>

export class FieldMappingService {
  applyMapping(
    data: Record<string, unknown>,
    mappings: FieldMappings,
    entity: MappingEntity,
    mode: MappingMode = MappingMode.RECEIVE
  ): Record<string, unknown> {
    const entityFieldMappings = mappings[entity]

    if (!entityFieldMappings || !entityFieldMappings.length) {
      return data
    }

    const newData: Record<string, unknown> = { ...data }

    entityFieldMappings.forEach(({ sourceField, destinationField }) => {
      let sourcePath: string[] = sourceField.split('.')
      let destinationPath: string[] = destinationField.split('.')

      if (mode === MappingMode.SEND) {
        sourcePath = destinationField.split('.')
        destinationPath = sourceField.split('.')
      }

      let value = newData

      sourcePath.forEach(path => {
        if (value && typeof value === 'object' && path in value) {
          value = value[path]
        } else {
          value = undefined
        }
      })

      if (value !== undefined) {
        let obj = newData

        for (let i = 0; i < destinationPath.length - 1; i++) {
          const key = destinationPath[i]
          obj[key] = obj[key] || {}
          obj = obj[key]
        }

        obj[destinationPath[destinationPath.length - 1]] = value
      }
    })

    return newData
  }
}